1. Field of the Invention
The present invention relates to a processional travel control apparatus which allows processional travel with a leading vehicle driven by a driver and at least one succeeding vehicle automatically following the leading vehicle, which handles the leading vehicle and the succeeding vehicle as a vehicle group, and which has a vehicle group identifying device to distinguish this vehicle group from another group.
This application is based on Japanese Patent Application No. Hei 11-127786.
2. Description of the Related Art
In recent years, environmental problems have been highlighted, and a technique for sharing electric vehicles within a certain area has been proposed to reduce problems of air pollution and traffic congestion. This type of technique for using shared vehicles requires a port (parking lot) for lending and returning the shared vehicles, and it is necessary to arrange a certain number of vehicles in each of these ports with respect to their utilization by users.
Generally, it is expected that ports for parking shared vehicles for this purpose will be provided in places where users converge, for example, in the vicinity of a train station and the like. There is no problem if the usage time and usage frequency by the users are consistent in each port, however, if there is any variance, then there is a situation in which shared vehicles accumulate in a certain port. To solve this problem, a technique is proposed for arranging shared vehicles available for rent in appropriate ports as evenly as possible, whereby the vehicles are moved between ports by having a vehicle driven by a driver at the head of a procession and a plurality of driverless vehicles following (refer to Japanese Patent Application, First Publication No. Hei. 5- 170008).
When travelling in a procession where succeeding vehicles follow a leading vehicle at the head, a system is used in which the succeeding vehicles trace the path of the leading vehicle. The leading vehicle sends vehicle speed, steering angle, vehicle position coordinates, direction, amount of torque required, brake pressure, and the like by vehicle to vehicle communication, to the succeeding vehicles, and the succeeding vehicles follow the leading vehicle while correcting the position and direction information of vehicles in front obtained by radar.
In the conventional processional travel control system, the vehicle to vehicle communication between the vehicles traveling in a procession is limited to a specified frequency band, e.g., a frequency band of 2.484 MHz for a radio LAN for mobile communication. Even when a plurality of processions of vehicles travel while conducting the vehicle to vehicle communication, radio interference does not generally occur because the coverage of radio waves for a radio LAN is limited to approximately several hundred meters. However, when the processions travel in a narrow area within the coverage of the radio waves, the radio interference may occur because the frequency band for a radio LAN is restricted as mentioned above.
To avoid this, a control apparatus may control the entire system, and may manage departure times and routes so that a plurality of processions of vehicles do not cross and do not travel parallel to each other. However, this system lacks flexibility, and may cause problems, e.g., when the processions of vehicles encounter each other as traffic conditions vary.
Further, the succeeding vehicles follow the leading vehicle while correcting the position and direction information of vehicles in front obtained by radar, and while detecting the relationship of the positions between the succeeding vehicles and the leading vehicle. In this case, there is the problem that the succeeding vehicles may receive radio waves transmitted from radar devices of the vehicles in another procession, which may cause an error in distinguishing the leading vehicle from the others.
It is therefore an object of the present invention to provide a processional travel control apparatus which can distinguish respective vehicle groups traveling in processions.
In a first aspect of the invention, the processional travel control apparatus allows processional travel with a leading vehicle (101, 101A, and 101B in the embodiments) driven by a driver and at least one succeeding vehicle (102, 102A, 102B, 103, 103A, and 103B in the embodiments) automatically following the leading vehicle, while maintaining distances and directions between the vehicles by means of radar devices (a laser radar 2, and a reflector 3 in the embodiments). The leading vehicle and the succeeding vehicle(s) constitute a group (first and second vehicle groups A and B in the embodiment). Each of the vehicles comprises a vehicle group identifying device for distinguishing a vehicle group from another vehicle group, the vehicle group identifying device (the radar device which can switch modulation as shown in FIG. 14) preventing radio interference between the groups during processional travel.
According to this construction, by means of the vehicle group identifying device, the vehicles which constitute the vehicle group can determine whether the data from the radar device is sent from their own vehicle group or not.
Even when vehicle groups approach each other, the interference in the radio data, transmitted from the radar device, with those from vehicles in another vehicle group, can be prevented. Therefore, the processional travel can be reliably conducted without being affected by another procession.
In a second aspect of the invention, the processional travel control apparatus allows processional travel with a leading vehicle driven by a driver and at least one succeeding vehicle automatically following the leading vehicle, while the vehicles communicate with each other by vehicle to vehicle communication. The leading vehicle and the succeeding vehicles constitute a group. Each of the vehicles comprises a vehicle group identifying device for distinguishing a vehicle group from another vehicle group, the vehicle group identifying device preventing radio interference between the groups during the processional travel.
The vehicle group identifying device uses, e.g., vehicle to vehicle communication using multi-channel communication (shown in FIGS. 5A, 5B), vehicle to vehicle communication using a spread spectrum (shown in FIGS. 6A, 6B), or a technique for adjusting communication timings and interrupting the communication (shown in FIG. 11).
According to this construction, by means of the vehicle group identifying device, the vehicles which constitute the vehicle group can determine whether the data from the radar device is sent from their own vehicle group or not.
Even when vehicle groups approach each other, radio interference in the vehicle to vehicle communication can be prevented, and the problem that the vehicles receive the data transmitted from vehicles in other vehicle group can be avoided.
In a third aspect of the invention, the processional travel control apparatus allows processional travel with a leading vehicle driven by a driver and at least one succeeding vehicle automatically following the leading vehicle, while the vehicles communicate with each other by vehicle to vehicle communication, and while maintaining distances and directions between the vehicles by means of radar devices. The leading vehicle and the succeeding vehicles constitute a group. Each of the vehicles comprises a vehicle group identifying device for distinguishing a vehicle group from another vehicle group, the vehicle group identifying device preventing radio interference between the groups during the processional travel.
According to this construction, by means of the vehicle group identifying device, the vehicles which constitute the vehicle group can determine whether the data in the vehicle to vehicle communication, or from the radar device is sent from their own vehicle group or not.
Even when vehicle groups approach each other, the radio interference in the vehicle to vehicle communication can be prevented, and the problem that the vehicles receive the radar waves from radar devices of vehicles in other vehicle groups can be avoided.
In a fourth aspect of the invention, the apparatus further comprises: a control device (e.g., a control device K in the embodiments) for detecting the position of a traveling vehicle group; and an approach determining device (e.g., step S43 in the embodiments) for determining whether the vehicle group is approaching another vehicle group so that radio interference will occur in vehicle to vehicle communication or in communication using radar devices in the vehicle group. When the approach determining device determines that the vehicle groups are approaching each other so that the radio interference will occur, the vehicle group identifying device identifies the respective vehicle groups which approach each other when traveling in processions.
According to this construction, the approach determining device determines whether the radio interference between the vehicle groups which approach each other will occur or not. Only when the radio interference will occur, the vehicle group identifying device identifies the respective vehicle groups. Thus, the invention simplifies the control of identifying the respective vehicle groups.